JOHOR BARU: The source of a "strange odour" at SK Sungai Tiram here is still being investigated, says Johor Environment Department (DOE) director Dr Mohd Famey Yusoff.

He said initial investigations did not find any illegal dumping or scheduled waste disposal in the school's surroundings in Kampung Sungai Tiram, Ulu Tiram.

"We are monitoring the situation with the hazardous material unit and the Pasir Gudang City Council (MBPG) and found that the samples of air and water taken from the river in the village are normal.

"The DOE has yet to determine the source of the odour. We are using drones to identify whether there are illegal dumping grounds or discharge from factories," he said.

Mohd Famey added that there were initial concerns from the authorities that an unlicensed used cooking oil processing factory, located in the village, was involved in the matter after several tanks were found at the premises.

He said that no waste or discharge was found at the site and the drain in the area was not connected to the river.

He also said that MBPG had taken action against the factory on Wednesday (Aug 2) for operating without a licence.

On Tuesday (Aug 2), 24 pupils, two teachers and two canteen staff at SK Sungai Tiram had to seek medical attention after suffering from dizzy spells and vomiting due to a strange odour in the area.

Students and teachers were told to evacuate the school while authorities tested the air and water quality.